Civil Air, the union representing air traffic controllers, and the SA state government said it would lead to a loss of controllers with local knowledge when guiding planes in and out of the airports at Adelaide, Parafield and Edinburgh.

Adelaide delegate Phil Brooke said the controllers in Adelaide operated four radar consoles and dealt with pilots on commercial flights, RAAF planes, light aircraft, as well as rescue helicopters and fire bombers.

"In an emergency, local knowledge kicks in - we know where the high terrain is, where fog builds up,'' he said.

Airservices Australia said the relocation of controllers did not include those who worked in towers at each of the airports.

Spokesman Rob Walker said a national increase in air traffic meant an upgraded and centralised system was being rolled out across Australia.